Carbon Explorers are ocean science geekology to the max. They drift with ocean currents, descend as deep as a kilometer to record particulate carbon, then return to the surface at programmed intervals and report by phoning home via satellite. Carbon Explorers have scored notable successes in understanding the ocean’s carbon cycle.
Explorers #1 and #2 were deployed in the North Pacific in 2001 and recorded a spectacular plankton bloom brought to life by an iron-rich dust storm from the Gobi Desert, a long-described process never before directly measured in this direct patient drifter manner.
In 2002, Explorers were part of the Southern Ocean Iron Experiment, providing the direct evidence of the replenishment and restoration effect of intentional additions of iron for the beneficial purpose of ocean pasture restoration. Two Explorers continued reporting another year, one eventually frozen in and wintering under the Antarctic ice shelf. Other Explorers have sent back valuable data from the Atlantic and elsewhere in the Pacific.
The track record is not all rosy. In 2004, as Bishop launched a Carbon Explorer in Hawaiian waters from the RV Kilo Moana, he messed up the launch and the instrument slammed into one of the ship’s twin hulls and sank, never to be heard from again. “Never allow the principal investigator to do real work,” Bishop later remarked.
The key instrument on the carbon explorers is crazy simple. It is a PIC (particulate inorganic carbon) sensor, it counts particles in the water such as plankton shells and other calcium carbonate (CaCO3) debris ten times a second. As a simple polarizing laser beam passes through the debris, the unusual refraction of CaCO3 gives the light a twist, allowing it to slip through a second polarizing filter that blocks other light.
The detector records only inorganic carbon particles. Naturally lots of side by side calibration studies have taken place so that this single measurement serves as a reliable proxy for a whole raft of particles.
Bishop notes, “Every day organisms swim up from the deep to feed,” says Bishop. “The process results in a huge amount of organic carbon that rides sinking particles from the sunlit layer into deeper water” – some 10 quadrillion grams of carbon globally each year – “ and no one has sampled this variability.” NOT SO Dr. Bishop we have, as you well know!
Time to board the Canadian research vessel John P. Tully. In February two Carbon Explorers were relaunched at the same station as the original Carbon Explorers and are reporting daily from the North Pacific.
Our ocean pasture restoration project in the village ocean pasture west of Haida Gwaii was far more than an order of magnitude larger than the experiments Bishop and the Carbon Explorers have worked with. In our largest and most extensive and intensively studied iron replenishment and restoration project we used instruments very similar to the Carbon Explorer.
As well our research ship stayed with the bloom for the longest time in history that a research ship has ever stayed with and studied a large pelagic plankton bloom. Unlike the lackadaisical Canadian government research ships that Bishop has worked on with his Carbon Explorers where the Canadian research ships allow science for only 7.5 hours per day our ship and crew manned the science stations 24/7 for months on end.
Our results are being working on now but preliminary analysis shows that the Old Massett Haida bloom was a spectacular success. Plus 20 robots we left in the bloom are still reporting back hourly!